Nikola tesla



(No Model.)

N. TESLA. ALTERNATING CURRENT ELECTRO MAGNETIC MOTOR.

No. 433,700. Patented Aug. 5, 1890.

UNITED STATES PATENT OFFICE.

NIKOLA TESLA, OF NEWV YORK, N. Y., ASSIGNOR TO THE TESLA ELECTRICCOMPANY, OF SAME PLACE.

ALTERNATING CURRENT ELECTRO-MAGNETIC MQTOR.

SPECIFICATION forming part of Letters Patent No. 433,700, dated August5, 1890.

Application filed March 26, 1890- Serial 1510.345388- (N model.)

To all whom it may concern.-

Be it known that I, NIKOLA TESLA, a subject of the Emperor ofAustria-I-Iungary, from Smiljan, Lika, border country of Austria-Hungary, residing at New York,in the county and State of New York, haveinvented certain new and useful Improvements in Alternating- CurrentElectro-Magnetic Motors, of which the following is a specification,referencebein g 1c had to the drawings accompanying and forming a partof the same.

This invention is an improvement in that class of electro-magneticmotors in which the rotation is produced by the progressive mover5 mentor effect of the maximum magnetic points or poles produced by theconjoint action or effect of two energizing circuits through which arepassed alternating currents, or currents of rapidly-varyin g strength ofa kindred nature.

The improvements subject of this application are more particularlyapplicable to that class of motors in which two or more sets ofenergizing-magnets are employed, and in 2 5 which by artificial means acertain interval of time is made to elapse between the respect ivemaximum or minimum periods or phases of their magnetic attraction oreffect. This interval or difference in phase between the two sets ofmagnets, when artificially produced, is limited in extent. It isdesirable, however, for the economical working of such motors that thestrength or attraction of one set of magnets should be maximum at thetime when that of the other set is minimum and conversely; but theseconditions have not heretofore been realized except in cases wh ere thetwo currents have been obtained from independent sources in the same ordifferent machines.

The object of the present invention is to establish conditions morenearly approaching the theoretical requirements of perfect working, or,in other words, to produce artificially a difference of magnetic phaseby means of a current from a single primary source suffi cient in extentto meet the requirements of practical and economical working.

In carrying out my invention I employ a motor with two sets ofenergizing or field magnets, each wound with coils connected with asource of alternating or rapidly-varying currents, but forming twoseparate paths or circuits. The magnets of one set I profeet to acertain extent from the energizing action of the current by means of amagnetic shield or screen interposed between the magnet and itsenergizing-coil. This shield is properly adapted to the conditions ofparticular cases, so as to shield 'or protect the main core frommagnetization until it has become itself saturated and no longer capableof containing all the lines of force produced by the current. By thismeans it will be seen that the energizing action begins in the protectedset of magnets a certain arbitrarily-determined period of time laterthan in the other, and that by this means alone or in conjunction withother means or devices heretofore employed a practically-economicaldifference of magnetic phase may readily be secured.

The nature and operation of the invention will be more fully explainedby reference to theaccompanying drawings.

Figure 1 is a view of a motor, partly in section, with a diagramillustrating the invention. Fig. 2 is a similar view of a modificationof the same.

In Fig. 1, which exhibits the simplest form of the invention, A A is thefield-magnet of a motor, having, say, eight poles or inwardlyprojectingcores B and C. The cores 13 form one set of magnets and are energized bycoils D. The cores C, forming the other set, are energized by coils E,and the coils are connected, preferably, in series with one another, intwo derived or branched circuits F G, re spectively, from a suitablesource of current) Each coil E is surrounded by a magnetic shield H,which is preferably composed of an annealed, insulated, or oxidized ironwire wrapped or wound on the coils in the manner indicated, so as toform a closed magnetic circuit around the coils and between the same andthe magnetic cores C. Between the pole pieces or cores B C is mountedthe armature K,which,asis usual in this type of machines, is wound withcoils L closed upon themselves. The operation resulting from thisdisposition is as follows: If a current impulse be di 10o rected throughthe two circuits of the motor, it will quickly energize the cores B, butnot so the cores 0, for the reason that in passing through the coils Ethere is encountered the influence of the closed magnetic circuitsformed by the shields II. The first effect is to effectively retard thecurrent impulse in circuit G, while at the same time the proportion ofcurrent which does pass does not magnetize the cores 0, which areshielded or screened by the shields H. As the increasing electro-motiveforce then urges more current through the coils E, the iron wire Hbecomes magnetically saturated and incapable of carrying all the linesof force, and hence ceases to protect the cores 0, which becomemagnetized, developing their maximum effect after an interval of timesubsequent to the similar manifestation of strength in the other set ofmagnets, the extent of which is arbitrarily determined by the thicknessof the shield H, and other well-understood conditions.

From the above it will be seen that the apparatus or device acts in twoways. First, by retarding the current, and, second, by retarding themagnetization of one set of the cores, from which its effectiveness willreadily apear. p Many modifications of the principle of this inventionare possible. One useful and effi- I cient application of the inventionis shown in Fig. 2. In said figure a motor is shown similar in allrespects to that above described, ex cept that the iron wire H, which iswrapped around the coils E, is in this case connected in series with thecoils D. The iron-wire coils II, are connected and wound, so as to havelittle or no self-induction, and being added to the resistance of thecircuit F the action of the current in that circuit will beaccelerated,while in the other circuit G it will be retarded. The shieldH may be made in many forms, as will be understood, and used indifferent Ways, as appears from the foregoing description. I do not,however,limitmyself to any specific form or arrangement; but

WVhat I claim is- 1. In an alternating-current motor having twoenergizing-circuits, the combination,with the magnetic cores and coilsof one of the circuits, of interposed magnetic shields orscreens forretarding the magnetization of said cores, as set forth.

2. In an alternating-current motor having two energizing-circuits, thecombination,with

the magnetic cores and the coils of one of the" circuits wound thereon,of magnetic shields or coils wound around said coils at right a11- glesto their convolutions, as set forth.

3. In an alternating-current motor having two energizing-circuits, thecombinatiomwith the magnetic cores and the coils of one of the circuitswhich energize the said cores, of mag netic shields forming closedmagnetic circuits around the coils and interposed between the coils andcores, as set forth.

4. In an alternating-current motor having two energizing-circuitsderived from the same source, the combination,with the cores and thecoils of one of the circuits that energizes the same, of insulatediron-wire coils wound 011 the said energizing-coils at right angles totheir convolutions and connected up in series with the coils of theother energizing-circuit,

as set forth. I

NIKOLA TESLA. Witnesses:

RoB'r. F. GAYLORD, PARKER W. PAGE.

